import java.sql.*;

public class Main {
    public static void main(String[] args) {
        Connection root = null;
        PreparedStatement preparedStatement = null;
        ResultSet resultSet = null;

        //jdbc
        //1，加载驱动
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            //2.创建链接
            String url = "jdbc:mysql://127.0.0.1:3306/jdbc?characterEncoding=utf-8";
            root = DriverManager.getConnection(url, "root", "123456");
            if(root != null){
                System.out.println("连接成功");
            }

            //3，写sql
            String sql = " SELECT * FROM `user`";


            //4，预编译sql
            preparedStatement = root.prepareStatement(sql);

            //5，执行sql
            resultSet = preparedStatement.executeQuery();

            //6，遍历结果
            while(resultSet.next()){
                int id = resultSet.getInt(1);
                String name = resultSet.getString(2);
                String pass = resultSet.getString(3);
                System.out.println(id+"....." +name+"....."+pass);
            }


        } catch (ClassNotFoundException e) {
            throw new RuntimeException(e);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }finally {
            //7.关闭资源
            try {
                if (resultSet != null){
                    resultSet.close();
                }
                if (preparedStatement != null){
                    preparedStatement.close();
                }
                if(root != null){
                    root.close();
                }
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }
        }
    }
}